1. Field of Invention
This invention relates to repair, maintenance and modifications of oil and gas field hardware, located in remote, inhospitable environment.
2. Description of Prior Art
Oil and Gas Field Production and Injection Wells:
North America has the highest concentration of active oil and gas wells in the world. They range in age from 50 years to recent. Most of these wells have low carbon steel casings and liners in them. Wear and tearxe2x80x94both mechanical and electrochemical (corrosion)xe2x80x94on the casings and liners are endemic to drilling and production operations. In most cases, casing or liner failure leads to cessation of operations at that well.
The traditional method that has been widely used for decades consists of spotting cement slurry in the defective interval and xe2x80x9csqueezingxe2x80x9d it through the defect to set and plug the leak. Many times it takes more than one attempt to seal the leak and can involve several days of well down time; sometimes the defect cannot be successfully repaired using this method. Moreover, casing or liner surface damage caused by post squeeze drilling and cleaning operation can set up corrosion cells and future problems. Since generally no visual evaluation of the problem is made, guess work plays a heavy role in the solution.
Another method of repair, sometimes used, consists of lining the inside of casing with liners. A special alloy liner has been used successfully in some cases and poly liners in some others. They are expensive and lack collapse strength; poly liners cause reduction of internal diameter so packers or bridge plugs cannot go through them and have low strength/bulk ratio.
Pipelinesxe2x80x94Onshore:
There are over 170,000 miles of pipelines in U.S. alone. They require periodic maintenance to avoid long shut downs and environmental damage. The present method of repair involves digging out the buried pipe, plugging the line on both sides of the defective section, redirecting the flow through a temporary bypass, removing the damaged section, repairing and replacing the section. The process is expensive and time consuming.
Pipelinesxe2x80x94Offshore:
Offshore pipelines are laid on the ocean floor. When a section of the line develops inevitable problem, one of the following three methods is currently used to repair it:
the defective section is raised to water surface, removed and replaced.
a diver/welder repairs the defect by under water welding.
specially manufactured mechanical connectors are used to repair the lines.
These methods are expensive and time consuming and exposes divers to risks.
Offshore Submarine Platform Structures:
The risers as well as platform structural members, such as tubular chords, braces and their weld joints require periodic inspection and maintenance. Any cracks or other defects are currently repaired by divers/welders. The process is expensive and exposes the divers to risks.
In accordance with the present invention, an oil and gas field hardware repair, maintenance and modification system and process, combining principles of oil field operations, coiled tubing, robotics and video technologies, extend an operator""s real time visual contact and operations control to remote and inhospitable work area, . By doing so, said system and process provide a viable, faster, safer and cost effective alternative to prevalent oil and gas field practices.
Accordingly, besides the objects and advantages of providing a viable, faster, safer and cost effective alternative, several other objects and advantages of present invention are:
a) to provide a way for remote visual reconnaissance, diagnosis and evaluation of hardware problems;
b) to provide commensurate solution to specific local problem and to reinforce the problem area with corrosion resistant metal;
c) to provide a solution technique that is unaffected by presence of porous formations behind casings in wells;
d) to avoid drilling inside casing for cement clean up and thus avoid setting up potential corrosion cells leading to new leaks;
e) to avoid reducing casing internal diameter to a point, where it hinders subsequent use of packers and bridge plugs;
f) to reduce down time;
g) to increase probability of successful casing repair in first attempt;
h) to provide a basis for innovative preventive maintenance program;
i) to provide a cost effective alternative method to repair pipelines and offshore submarine structures.